For various applications in the field of the production and use of cement, a variety of mortar systems are provided, it being possible for a distinction to be made between, for example, two-component and one-component dry mortar systems. With regard to the use of two-component (2 K) dry mortar systems, there is a risk of mixing errors, since the two components of the dry mortar system are formulated specifically for specific mixing ratios. For specialist applications (e.g., cementitious seals in assembly), the mortar systems used include cementitious one-component (1 K) dry mortar systems having a high polymer fraction (>20, in some cases up to 40 wt %). Such one-component dry mortar systems are powder products which are formulated at the production works and which, prior to application, are prepared by mixing with water, giving them a workable consistency.
The polymers used are, generally, redispersible dispersion powders, polymer fibers, methylcelluloses, starch ethers, dispersants, and/or polymers with a thickening action. The high fraction of polymers is a result, for example, of the specific technical requirements imposed on such one-component waterproofing systems, as are required for water-impermeable products, intended for liquid working, in assembly before sticking ceramic tiles (e.g., DIN EN 14891).
It is known in this context that a high polymer content on the part of cementitious mortar systems leads to disruptions to the hydration profile (hardening) and/or to the kinetics of setting. As a result of the composition of the polymers (specifically monomers) and their additization, there is generally a significant influence on the reactivity of the cementitious binder components. The hardening of cementitious binder systems is generally accompanied by formation of what are called hydrate phases, owing to processes of dissolution and recrystallization. Water is bound chemically in the hydrate phases formed. The microstructure of the crystalline hydration products is responsible for the strength, and development of strength, of cementitious binder systems.
For the working properties of such one-component waterproofing slurries, for example, it is important, moreover, to enable an appropriate working time. The working time here is understood as the period between contacting of the dry mortar with water and the time at which the mortar can no longer be reliably worked, in other words until it loses its workable consistency as a result of the ensuing reaction. At the end of the working time, the hydration products that form begin to develop the microstructure, and the product can no longer be reliably worked.
An appropriate working time may generally be set using various chemical additions (including fruit acids, phosphates, etc.). These additions, however, may likewise have adverse consequences for the setting reaction and for the subsequent hydration profile. The retardant effect of such additions derives, for example, from the complexing of particular reactants (in general, polyvalent ions), which are then no longer available for the formation of hydration products in the course of hardening.
For example, there are known cementitious 1 K mortar formulations (including waterproofing slurry systems) which have a polymer fraction >20 wt %. These systems include, firstly, pure Portland cement-based systems (OPC systems) having a polymer fraction of up to about 30 wt %. Such systems do have very long working times (>4 hours), but only in conjunction with a very slow curing (>4 hours), which is untenable in practice. Known, secondly, are products which are based on ternary binder systems consisting of Portland cement (OPC; principal binder), high-alumina cement (HAC) and a sulfate carrier. These systems as well have a polymer fraction >20 wt % and up to 40 wt %. A disadvantage with such systems is often the short working time (about 30 minutes) which is untenable in practice for a sufficiently short cure time.
Also known is an innovative high-alumina cement (ettringite former) for binary binder systems (HAC+sulfate carrier), with the particular advantage that the use of Portland cement in the formulation is superfluous, the special reactivity of a binder system of this kind being described in FR2839066 (page 10/11) and DE60304041 (page 7/8).
Also known are guide formulations from raw materials manufacturers for cementitious 1 K mortar systems, with the focus on waterproofing slurries.
For example, a guide formulation from BASF (25.07.2011) describes a ternary binder system based on OPC (principal constituent), HAC, and sulfate carrier. The polymer fraction here is about 33 wt %. The dispersion powder used is a powder based on a copolymer of an acrylic ester and styrene. Disadvantages associated with this guide formulation, however, are the late foot-traffic accessibility and the long period before application of a second coat, especially at low temperatures and high humidity, and also a too short working time at high temperatures.
Thus, disclosed herein are improved binder systems and dry mortars featuring improved setting characteristics.